Microphone module with sound pipe

ABSTRACT

A microphone module has a substrate with an aperture to allow sound waves to pass through the substrate, a lid mounted to the substrate to define a first interior volume, a microphone mounted to the substrate within the first interior volume, and a housing coupled to the substrate and covering the aperture. The housing forms a second interior volume and includes an acoustic port configured to allow sound to enter the second interior volume. The module further includes a pipe extending from the acoustic port in the housing, and at least one exterior interface pad outside of the second interior volume. The pipe has an open end to receive sound waves and direct them toward the acoustic port in the housing. Moreover, the at least one exterior interface pad electrically couples to the microphone.

PRIORITY

This patent application is a divisional application of U.S. patentapplication Ser. No. 14/223,996, filed on Mar. 24, 2014, and namingKieran P Harney, Dipak Sengupta, Brian Moss, and Alain Guery asinventors, and entitled “MICROPHONE MODULE WITH SOUND PIPE”, which is adivisional application of U.S. patent application Ser. No. 13/661,402,filed on Oct. 26, 2012, and naming Kieran P Harney, Dipak Sengupta,Brian Moss, and Alain Guery as inventors, and entitled “MICROPHONEMODULE WITH SOUND PIPE”, which claims priority from provisional U.S.patent application number 61/561,121, filed Nov. 17, 2011, entitled,“MICROPHONE MODULE,” and naming Kieran P Harney, Dipak Sengupta, BrianMoss, and Alain Guery as inventors, the disclosure of which isincorporated herein, in its entirety, by reference.

FIELD OF THE INVENTION

The invention generally relates to microphones and, more particularly,the invention relates to a structure for housing microphones.

BACKGROUND OF THE INVENTION

Small microphone systems have a broad range of applications, includinguse in hearing aids, Bluetooth headsets, and mobile phones. Typicalmicrophone systems include a microphone element, such as amicroelectromechanical system microphone (also known as a “micromachinedmicrophone,” “silicon microphone,” or “MEMS microphone”). The microphonemay include on-board circuitry to process the microphone element'selectrical output signals, or may be packaged with another circuit inthe same package.

Many microphone packages have a base and a lid, and are configured to bemounted onto a larger substrate, such as a printed circuit board orother surface of a larger system. For example, a packaged microphone maybe mounted to an interior surface of a host system, such as cellularphone. Placement of the microphone system/packaged microphone within thehost system is important, however, to ensure that acoustic signals canreach their internal microphone element. If spaced too far from a hostport that receives those signals (e.g., the mouthpiece of a mobiletelephone), the microphone element may not adequately receive andconvert the input acoustic signal.

SUMMARY OF VARIOUS EMBODIMENTS

In accordance with one embodiment of the invention, a microphone modulehas a substrate with a first side and a second side opposite the firstside. The substrate has an aperture extending from the first side to thesecond side to allow sound waves to pass through the substrate. Themodule also includes a lid mounted to the first side to define a firstinterior volume, a microphone mounted to the first side and within thefirst interior volume, and a housing coupled to the second side andcovering the aperture. The housing and second side form a secondinterior volume, while the housing includes an acoustic port configuredto allow sound to enter the second interior volume. The module furtherhas a pipe extending from the acoustic port in the housing, and at leastone exterior interface pad on the second side and outside of the secondinterior volume. The pipe has an open end to receive sound waves anddirect them toward the acoustic port in the housing. In addition, the atleast one exterior interface pad is electrically coupled to themicrophone.

The housing may have a top and at least one sidewall. The acoustic portthus may be disposed through the top of the housing, and the pipe mayextend from the top of the housing. Alternatively, or in addition, theacoustic port may be disposed through the sidewall of the housing, andthe pipe may extend from the at least one sidewall of the housing. Thehousing also may include a second acoustic port with a second pipeextending therefrom. Among other shapes, the pipe may be straight.

The microphone may include a MEMS microphone, and the module further mayinclude a circuit chip coupled with the first side of the substrate.Moreover, the lid may include conductive material that is electricallyconnected with the substrate. For example, the substrate may have ametalized portion, and the lid may be formed from metal and beelectrically connected to the metalized portion of the substrate toprotect against electromagnetic interference.

The housing may take on any of a variety of different configurations.For example, the housing may include a flanged sound pipe where the pipehas a pipe volume that forms most of the second interior volume. In thiscase, the flanged pipe may be mounted substantially flush against thesecond side of the substrate. Moreover, the housing, which may cover nomore than a portion of the second side, may be formed at least in partfrom a conductive material.

In some embodiments, the microphone covers the aperture in thesubstrate. In addition or alternatively, at least one exterior interfacepad preferably is surface mountable. The internal components mayelectrically connect with the exterior interface pad in a number ofdifferent manners. For example, the module may have an interiorinterface pad within the first interior volume, a circuit chip withinthe interior volume, and first and second wire bonds within the interiorvolume. The first wire bond may electrically connect the microphone tothe circuit chip, while the second wire bond may electrically connectthe circuit chip to the interior interface pad. The microphone thus canelectrically connect with the exterior interface pad on the second sidethrough the first wire bond, circuit chip, second wire bond, andinterior interface pad.

In accordance with another embodiment of the invention, a microphonemodule has a substrate with a first side, and a second side opposite thefirst side. The substrate, which has a metalized portion, also has anaperture extending from the first side to the second side to allow soundwaves to pass through the substrate. The module further includes a lidmounted to the first side, a MEMS microphone mounted to the first sideand within the first interior volume, and a circuit chip coupled withthe first side of the substrate and electrically connected with themicrophone. The first side and lid are considered to define a firstinterior volume, and the lid is formed from a conductive material. Thelid is electrically connected to the metalized portion of the substrateto protect against electromagnetic interference. Also, in a mannersimilar to the MEMS microphone, the circuit chip also is mounted withinthe first interior volume. The module further has a housing coupled tothe second side and covering the aperture. The housing and second sideform a second interior volume, and the housing also has an acoustic portconfigured to allow sound to enter the second interior volume. Thehousing covers no more than a portion of the second side of thesubstrate. A pipe extends from the acoustic port in the housing. Thispipe has an open end to receive sound waves and direct them toward theacoustic port in the housing. In addition, the module also has at leastone exterior, surface mountable interface pad on the second side andoutside of the second interior volume. The at least one exteriorinterface pad electrically couples to the microphone.

In accordance with other embodiments of the invention, a microphonemodule has a substrate with an aperture to allow sound waves to passthrough the substrate, a lid mounted to the substrate to define a firstinterior volume, a microphone mounted to the substrate within the firstinterior volume, and a housing coupled to the substrate and covering theaperture. The housing forms a second interior volume and includes anacoustic port configured to allow sound to enter the second interiorvolume. The module further includes a pipe extending from the acousticport in the housing, and at least one exterior interface pad outside ofthe second interior volume. The pipe has an open end to receive soundwaves and direct them toward the acoustic port in the housing. Moreover,the at least one exterior interface pad electrically couples to themicrophone.

BRIEF DESCRIPTION OF THE DRAWINGS

Those skilled in the art should more fully appreciate advantages ofvarious embodiments of the invention from the following “Description ofIllustrative Embodiments,” discussed with reference to the drawingssummarized immediately below.

FIGS. 1A and 1B schematically illustrate a prior art MEMS microphone;

FIG. 2 schematically illustrates a prior art packaged microphone;

FIG. 3 schematically illustrates a prior art packaged microphone mountedon a circuit board along with other components;

FIGS. 4A and 4B schematically illustrate an embodiment of a microphonemodule;

FIG. 5A-5H schematically illustrate various microphone moduleembodiments;

FIGS. 6A-6D schematically illustrate various microphone moduleembodiments;

FIG. 6E schematically illustrates an embodiment of a flanged sound pipe;

FIGS. 7A-7D schematically illustrate various microphone moduleembodiments;

FIG. 8 schematically illustrates an embodiment of a microphone module;

FIG. 9 schematically illustrates an embodiment of a microphone module;

FIG. 10 schematically illustrates an embodiment of a microphone module;

FIG. 11 schematically illustrates an embodiment of a microphone module;

FIGS. 12A-12C schematically illustrate an embodiment of a microphonemodule;

FIGS. 13A-13C schematically illustrate an embodiment of a microphonemodule;

FIG. 14 schematically illustrates an embodiment of a microphone modulewithin a host system;

FIGS. 15A and 15B schematically illustrate an embodiment of a microphonemodule;

FIGS. 16A and 16B schematically illustrate an embodiment of a microphonemodule;

FIGS. 17A and 17B schematically illustrate an embodiment of a microphonemodule;

FIGS. 18 and 19 schematically illustrate an embodiment of a microphonemodule;

FIGS. 20A-20C schematically illustrate an embodiment of a microphonemodule;

FIG. 20D schematically illustrates an embodiment of a microphone module;

FIGS. 21A and 21B schematically illustrate an embodiment of a microphonemodule;

FIGS. 22A and 22B schematically illustrate an embodiment of a microphonemodule;

FIGS. 23A and 23B schematically illustrate an embodiment of a microphonemodule;

FIGS. 24A and 24B schematically illustrate an embodiment of a microphonemodule;

FIGS. 25A and 25B schematically illustrate an embodiment of a microphonemodule;

FIGS. 26A and 26B schematically illustrate an embodiment of a microphonemodule;

FIG. 27 schematically illustrates an embodiment of a microphone module;

FIG. 28 schematically illustrates an embodiment of a microphone module;

FIG. 29 schematically illustrates an embodiment of a microphone module;

FIG. 30 schematically illustrates an embodiment of a microphone module;

FIG. 31 schematically illustrates an embodiment of a microphone module;

FIGS. 32A-32E schematically illustrate ways by which a sound pipe mayinterface to a microphone module.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Various microphone module embodiments may be mounted into a host systemin a variety of ways, consequently providing to a system designerflexibility and options not available with prior art microphonepackages. To that end, in various embodiments, the microphone module hasat least one acoustic port that is acoustically coupled to a microphoneelement within its interior. In some embodiments, the acoustic portincludes a structure that is configured to couple to a sound pipe (oracoustic waveguide) which may be used as-is, or which may be extended byattaching an additional length of sound pipe. The sound pipe guidesincoming sound to the acoustic port. As such, the microphone module maybe mounted within a larger system without requiring that its aperture beimmediately adjacent to the sound source, or directly adjacent to astructure with an aligned counterpart aperture. In fact, unlike variousprior art microphone packages known to the inventors, some embodimentsmay not need to be mounted to an underlying substrate.

A microphone (or “microphone element”) is a transducer that produceselectrical signals in response to impinging sound waves. The operationof the microphone depends on the ability of sound waves to reach themicrophone, and particularly the microphone's diaphragm, from the sourceof the sound. One type of microphone is a microelectromechanical system(or “MEMS”) microphone 100 (a/k/a “micromachined”), is schematicallyillustrated in perspective view in FIG. 1A, while FIG. 1B schematicallyillustrates a cross-section of the same microphone 100. Microphone 100includes a diaphragm 101 suspended by springs 102 above a backplate 104.The diaphragm 101 and backplate 104 are both conductive, and areelectrically isolated from each other. As such, the diaphragm 101 andbackplate 104 form a capacitor. It should be noted, however, that MEMSmicrophones can be configured in many different ways, and FIG. 1 issimply one particular way.

More specifically in the microphone 100, the diaphragm 101 and backplate104 form a variable capacitor. In operation, the diaphragm 101 vibratesin response to incident sound waves, thus changing the gap 105 betweenthe diaphragm 101 and backplate 105. Among other things, this meansthat, as the gap 105 narrows, the diaphragm 101 approaches the backplate104. The capacitance of the variable capacitor formed by the diaphragm101 and backplate 104 therefore varies with the impinging sound waves.The variable capacitance can be electronically processed to produce anelectrical signal representing the impinging sound waves, in ways wellknown in the art.

Prior art packages known to the inventors typically enclose themicrophone element (e.g., microphone 100) in a package having asubstrate and a lid, as schematically illustrated in FIG. 2. In thatfigure, a packaged microphone 200 has a microphone 203 mounted to asurface 201A of laminate substrate 201. The lid 202 and the surface 201Aof the substrate 201 define an interior volume surrounding themicrophone 203. The microphone 203 is physically coupled to thesubstrate 201, and also electrically coupled to the substrate 201 by oneor more wirebonds 204.

The substrate 201 includes an aperture 205 that permits sound waves intothe interior volume containing the microphone 203. Some embodiments mayalternately, or in addition, have an aperture in the lid.

The packaged microphone 200 may be mounted to printed circuit board 300,which often also includes other circuit elements 201, as schematicallyillustrated in FIG. 3. Alternatively, the packaged microphone 200 may bemounted to another surface within a system that hosts the microphonesystem 200. Incoming sound waves reach the microphone 203 by passingthrough an aperture 302 in the printed circuit board, and then throughthe aperture 205 in the substrate 201. As shown by FIG. 3, thisparticular example of a prior art packaging system 200 limits the systemdesigner's freedom of choice because the packaged system 200 must bemounted adjacent to (and in fact covering) the aperture 302 in theprinted circuit board.

In contrast, FIG. 4A schematically shows one embodiment of a microphonemodule 400 that provides a wider range of options for use in a hostsystem. In particular, the microphone module 400 includes an acousticport 412 to guide sound waves from a distal location to an interiorvolume of the system 400. To that end, the microphone module 400includes a substrate 401 supporting a microphone 403, a lid 406 coveringthe microphone 403, and a housing 410. In this embodiment, the housing410 includes two acoustic ports 412 configured to acoustically couplethe entire microphone module 400 to a source of incoming sound.

While some embodiments of an acoustic port include a short section ofsound pipe 413, which may be configured to attach to another section ofsound pipe 413, in other embodiments the acoustic port 412 is anaperture. The sound pipe typically has an open end to receive andacoustic signal, and an end attached to the acoustic port 412 in thehousing 410. The dimensions of the sound pipe may be defined, at leastin part, by the mechanical and acoustic characteristics of the hostsystem with which the microphone system will be used. Among otherthings, the length and diameter of the sound pipe can define acousticperformance, such as resonances that may in some cases be desirable. Asjust one example, in some embodiments, the sound pipe may have acircular cross-section with a diameter of 0.5 millimeters, and be fivemillimeters in length. The sound pipe may be straight, or may includeone or more curves, angles or bends.

Specifically, the module 400 has a substrate 401 having a first side401A and a second side 401B. The substrate 401 may be a laminate (e.g.,BT), or other material (e.g., FR-4, a pre-molded leadframe package base,or a ceramic carrier), and may include conductive elements to provideground, power, and/or other electrical interconnection for othercomponents of the microphone module 400. As another example, thesubstrate 401 acts as part of a Faraday Cage to provideelectromagnetically shield its internally mounted microphone 403.

The substrate 401 includes at least one aperture 402 extending betweenthe first side 401A and second side 401B. The microphone 403 and ancircuit chip/ASIC 404 are mounted to the first side, and the microphone403 preferably straddles/covers the aperture 402. Some embodiments,however, do not require the microphone 403 to cover the aperture 402.For example, the microphone 403 may be adjacent to but not cover theaperture 402.

The ASIC 404 is electrically coupled to the microphone 403 and processesthe output of the microphone 403. The output of the ASIC, in turn, iscoupled to one or more exterior interface pads 405 on the first side401A. The interface pads 405 may be coupled to a host system of whichthe microphone module 400 is a part. The host system may communicatewith the ASIC 404 and/or the microphone 403 via the interface pads 405.Another view of the interface pads 405 on the first surface 401A isschematically illustrated in FIG. 4B.

A lid 406 is mounted to the first surface 401 and covers the microphone403, ASIC 404, and aperture 402. Thus, the substrate 401 and lid 406form a first interior volume 407, which forms the majority of theback-volume for the microphone. The lid 406 may be formed from a varietyof materials, and may be a conductor or an insulator. For example, thelid may be a conductive metal lid (e.g., a solid metal lid), a plasticlid, a laminate, or a non-metal lid with conductive plating.

In some embodiments, some or all of the first surface 401A of thesubstrate 401 may be metallized so that the lid may be coupled to themetallized portion. This may serve to keep the lid 406 grounded, and mayserve to protect the microphone 403 or ASIC 404 against externalelectromagnetic interference (“EMI”). To that end, a solder or adhesive(e.g., a conductive epoxy) may secure the lid 406 to some part of themetalized portion of the substrate 401.

In the embodiment of FIG. 4A, the lid 406 does not cover the entirefirst surface 401A, and the interface pads 405 are outside of the lid406. In other words, the interface pads 405 are outside of the firstvolume 407. This leaves the interface pads 405 available for connectingto a host system, for example by wire bonds, soldered leads, surfacemounting to a printed circuit board (“PCB”), ACF attach (i.e.,attachment using an “Anisotropic Conductive Film”), epoxy attach orother electrical connection means known in the art. Accordingly, amongother things, the pads 405 are considered to be solderable.

The other side 401B of the substrate 401 includes a housing 410, whichcovers the aperture 402. The housing may include a variety of material,and may be a conductor or an insulator. For example, the housing may bea solid conductive metal structure, a plastic structure, or a non-metalstructure with conductive plating. The housing 410 may be of the samematerial as the lid 406, although that is not required.

In some embodiments, some or all of the second surface 401B of thesubstrate 401 may be metallized, so that the housing may be coupled tothe metallized portion. This may keep the housing 410 grounded, and mayprotect the microphone 403 or ASIC 404 against external electromagneticinterference. The housing 410 may be coupled to a metalized portion ofthe substrate 401 by solder or an adhesive, such as a conductive epoxy.

The housing 410 may cover the more of, or less than, the substrate'ssurface area than the lid 406. In some embodiments, however, the housing410 covers about the same surface area as that of the lid 406. Thesubstrate 401 and housing 410 form a second interior volume 411 throughwhich sound can traverse.

The housing 410 may be considered as having a top 410A (e.g., thehousing surface that is generally parallel with the substrate 401) and aplurality of sidewalls 410B (e.g., the housing surface that is generallyorthogonal to the substrate 401). The top 410A and sidewalls 410B meetat corners 410C. Of course, other embodiments may have housings with avariety of shapes, including rectangular, oval, round, or irregular, andmay include shapes with or without edges and/or corners. An acousticaperture 412 on a sidewall 410B is acoustically coupled to the secondvolume 411, and may be coupled to a sound pipe 413. The sound pipe 413guides sound waves from outside of the module 400 toward and into thesecond volume 411. The sound waves then pass through aperture 402 andimpinge on the diaphragm 101 of microphone 403. In some embodiments, anacoustic port 413 may be on the top wall 410A of the housing 410, on asidewall 410B of the housing, or at a corner 410C of the housing. Theacoustic port 413 shown in FIG. 4A as extending from the acousticaperture 412 on the top wall 410A may be used in addition to the soundpipe 413 extending from the side wall 410B, or as an alternative to thesound pipe 413 extending from the side wall 410B. In other words, thesound pipe 413 extending from the top wall 410A may be the only soundpipe 413 extending from the housing 410.

In this way, the microphone module 400 may be mounted in a host systemin a location that does not need to be immediately adjacent to anaperture or the source of the sound, and does not need to be mounted toa particular surface. Rather, the microphone module 400 may be mountedin any desired position within the host system, and the sound pipe canextend from the acoustic aperture 412 to the source of the sound andconduct the sound to the module 400. For example, as shown in FIG. 14, amicrophone module 400 may be mounted at a location 1402 within acellular telephone 1401. Alternately, the underlying system/host systemcould be other objects, such as a hearing aid, or a Bluetooth headset,to name but a few. A sound pipe 1403, which in this embodiment is atube, directs incoming sound from the mouthpiece 1403 of the cellularphone 1401 to the microphone module 400. The sound pipe and otheraspects of the microphone system design may be selected and optimized bythe designer of the microphone system, or a host system, to provide thedesired acoustic performance. Alternatively, rather than using a soundpipe, the system 1400 may have an aperture to allow sound to enter themicrophone.

An alternate embodiment of a microphone module 500 is schematicallyillustrated in FIGS. 5A and 5B. In this embodiment, interface pads 505are positioned on the same side of the substrate 501 as the housing 510,and yet are not within the housing 510. As noted above, this and otherembodiments may connect the interface pads 505 to an underlying system,for example by wire bonds, soldered leads, surface mounting to a printedcircuit board (“PCB”), ACF attach (i.e., attachment using an“Anisotropic Conductive Film”), epoxy attach or other electricalconnection means known in the art.

FIG. 5A also shows how the microphone 403 and circuit chip 404 connectwith the interface pads 505. Specifically, a first wire bond 507connects the microphone 403 to the circuit chip 404, while a second wirebond 507 connects the circuit chip 404 to an internal interconnectionpad 506. The interior interconnection pad 506 in turn is electricallyconnected with the external interface pad 505 through the substrate 401,thus electrically communicating the interior components (e.g., themicrophone 403 and circuit chip 404) with an underlying system (e.g.,the printed circuit board of a mobile telephone or hearing instrument).

Yet other embodiments are schematically illustrated in FIGS. 5C-5H.These and other embodiments can have features that can be combined. Theembodiment in FIGS. 5C and 5D includes two arrays of interface pads,505A and 505B, on the substrate 510 on either side of housing 511. Inthis illustration, the sound pipe 512 extends from the housing 510 in adirection normal to the page, and along a line that passes between theinterface pad arrays 505A and 505B. Another embodiment, schematicallyillustrated in FIGS. 5E and 5F, has arrays of interface pads 505C and505D on the same side of the substrate 520 as the lid 521, microphone403 and ASIC 507, and on opposite sides of the lid 521. Otherembodiments may have one or more interface pads 505, or arrays ofinterface pads 505, with some on one side of the substrate, and some onthe other side of the substrate.

Yet another embodiment is schematically illustrated in FIGS. 5G and 5H.In this embodiment, the microphone element 530 and ASIC 531 are onopposite sides of the substrate 532, with an interface pad array 505E onthe same side of the substrate 532 as the microphone element 530.Related embodiments could include an interface pad array 505 on the sideopposite the microphone element 530.

An alternate embodiment is schematically illustrated as microphonemodule 600 in FIGS. 6A-6D. This embodiment 600 includes a flanged soundpipe 601 rather than a housing 510/410/etc. (i.e., another type ofhousing). As discussed below with regard to FIG. 6E, the flanged soundpipe 601 has a flange 602, and a sound pipe 603 extending from theflange 602. Other components of the microphone module 600 are similar tomicrophone module 400 in FIGS. 4A-4B, including a substrate 401, lid406, microphone element 403, ASIC 404 and interface pads 405. Of course,the flanged sound pipe 601 also can be used with the embodimentsdiscussed with regard to FIGS. 5A-5H. In that case, like the embodimentof FIG. 4A-4B, the flanged sound pipe 601 is used in place of thehousing 510.

Unlike the comparable portion of the housing 401, however, the flange602 does not define an appreciable second volume with the substrate 401(i.e., it forms only a very small second volume or no second volume—ifthe second volume does not include the volume of the sound pipe 603).Instead, the flange 602 of flanged sound pipe 601 rests substantiallyflush against the substrate 401 such that the sound pipe 603 is adjacentto and in acoustic communication with the aperture 402. In this way, thesound pipe 603 guides sound from its distal end 604 to the microphone403.

This embodiment the sound pipe also includes a bend 605. The bend 605provides additional flexibility to a system designer by allowing thesound pipe to run from the microphone module 600 to a distal soundsource without requiring the sound pipe 601 to follow a straight linepath. The flange can be attached to the substrate using many differenttechniques know in the art, including soldering, conductive ornon-conductive adhesives, or other fixing methods. Alternatively, thesound pipe could have no flange and be attached directly to thesubstrate using known methods. Of course, rather than have a bend, thesound pipe could be straight, as in sound pipe 621 in the microphonemodule 620 in FIG. 6C.

An embodiment of a flanged sound pipe 651 is schematically illustratedby a perspective view in FIG. 6E, and includes flange 652 and sound pipe653. The flange 652 in this embodiment is generally planar, and isconfigured to mount to a face of a housing or substrate, or other planarsurface. The flange 652 is square, and is generally normal to the soundpipe 653. However, in other embodiments, the flange 652 could take avariety of shapes, and could be angled with respect to the sound pipe653.

The sound pipe 653 in this embodiment has a cross-section that iscircular, and flares slightly where it meets the flange 652. However,the shape of the cross-section could also be described by another conicsection, or be rectangular, to name just a few examples.

Another embodiment of a microphone module 700 is schematicallyillustrated in FIGS. 7A and 7B. The embodiment 700 has a flanged soundpipe 701, and is otherwise similar to the embodiments in FIGS. 5A-5H.

A similar embedment 720 is schematically illustrated in FIGS. 7C and 7D,except that the sound pipe 720 is straight, similar to the sound pipe620 in FIG. 6C. FIG. 7C shows sound pipe 721 in cross-section profile,and reveals that the cross-section is rectangular. However, thecross-section of a sound pipe, in a plane normal to its length, can takeany shape, including square, rectangular, conic-section, or any othershape. For example, FIG. 6E schematically illustrates a perspective viewof a flanged sound pipe 601 having a flange 602 and a sound pipe 603with a circular cross-section.

Some embodiments have more than one acoustic aperture. One suchembodiment is schematically illustrated as microphone module 800 in FIG.8. In this embodiment, the lid 806 and the housing 810 each have anacoustic aperture 813 and 820, respectively. The acoustic apertures 813and 820 can take the form of sound pipes, or could also be holes, or acombination of a sound pipe and a hole. As discussed above, rather thanextend from housing side 810B, the sound pipe 813A can extend from thetop side 810A of the housing 810. Moreover, as noted above, thisembodiment can have a single sound pipe/aperture combination rather thantwo (e.g., just a sound pipe/aperture combination 813 extending from thehousing 810).

Several embodiments may have multiple lids, housing and microphones. Forexample, a dual-module 900 is schematically illustrated in FIG. 9. Thedual module 900 has a single substrate 90 supporting two lids 901A and901B and two housings 910A and 910B. Each lid 901A and 901B houses amicrophone 903A and 903B, respectively, and an ASIC 904A and 904Brespectively. Each microphone 903A and 904B straddles an aperture, 902Aand 902B, respectively. Each housing 910A and 910B has an acoustic port913A and 913B, which are similar to the acoustic ports inpreviously-described embodiments. The dual-module 900 has at least oneinterface pad 905 that may serve one or both segments of the dualmodule. In this embodiment, the interface pad 905 is on the same side ofthe substrate as the lids 906A and 906B, but one or more pads 905 couldalso be on the other side, but outside the housing 910B. Someembodiments contain several interface pads 905, which can be independent(i.e., so that both microphones 903A and 904A are independentlyelectrically accessible). Moreover, some interface pads 905 may beindependent while other interface pads 905 are shared by the twomicrophones 903A and 904A. Although the embodiment in FIG. 9 shows twomicrophones, some embodiments may have three or more microphones, eachwith its own lid and housing. Alternately, some microphone systems mayhave multiple lids 906, but only a single corresponding housing 910.

In an alternate embodiment 1000, two housings 1010A and 1010E areacoustically coupled by a bridge 1020, as schematically illustrated inFIG. 10. The bridge 1020 allows a single acoustic aperture or sound pipe1013 to guide incoming sound signals to both housings, and ultimately totheir associated microphones. Alternately, the housings 1010A and 1010B,which are connected by bridge 1020, could be considered to be a singlehousing. The dual-module 1000 has at least one interface pad 1005 thatserves both segments of the dual module. In this embodiment, theinterface pad 1005 is on the same side of the substrate as the lids1006A and 1006B, but one or more pads could also be on the obverse side,but outside the housing 1010B.

Yet other dual-module embodiments may also have one or more acousticports 1130A and 1130E in their respective lids 1106A and 1106B, as indual-module 1100 as schematically illustrated in FIG. 11.

Other embodiments provide interface pads on a portion adjacent to a lid.For example, as shown in FIG. 12, a microphone system 1200 includes asubstrate 1201 supporting an ASIC 1202 with a stacked MEMS microphone1203 covered by a lid 1204. The substrate 1201 includes an aperture 1205(which may also be known as a “port hole”) acoustically coupled to anASIC aperture 1206 in ASIC 1202, so that sound may pass through thesubstrate aperture 1206 to reach microphone 1203. A number of interfacepads 1215 reside on the surface of substrate 1201, on the same side aslid 1204. Other embodiments, however, may have interface pads on theother side of the substrate 1201. One or both of the ASIC 1202 andmicrophone 1203 may be electrically coupled to the interface pads 1215to provide an accessible means of electrically communicating with a hostsystem.

As with other disclosed embodiments, the interface pads 1215 can beconnected by a variety of interconnect means, such as wire bonds,solder, epoxy or ACF to a printed circuit (“PC”) board, or a laminate,to name but a few. Some embodiments may include an array of interfacepads along an edge of the substrate, such that the interface pads may beinserted into a socket, such as a linear socket on a computer'sbackplane, for example. This embodiment 1200 may be used with a housingand/or a sound pipe (e.g., a flanged sound pipe) as illustrated in otherembodiments herein, but may also be surface-mounted—for example byinterface pads, or by coupling the substrate 1201 to a surface of a hostsystem. Therefore, the embodiment 1200 provides a host system designerwith considerable flexibility.

Various embodiments, including each of the embodiments described above,may include a filter in one or all of their substrate apertures,acoustic ports, and/or a sound pipes. One embodiment 1300 isschematically illustrate in FIGS. 13A-C, in which a substrate 1301supports/hosts an ASIC 1302 with a stacked MEMS microphone 1303 coveredby a lid 1304. As with other lids described above, the lid 1304 may beattached to the substrate 1301 to create a volume that is partiallyoccupied by the ASIC 1302 and microphone 1303.

In this embodiment, a filter material resides either within the aperture1306, or on a top or bottom face of substrate 1301 covering theaperture. In an embodiment with a laminate substrate, the filter may bepart of a laminate layer, or may be sandwiched between two laminatelayers, for example. Depending on its construction, the filter 1320 mayprevent objects, dust or other particulate matter, light, moisture orother environmental contaminants from passing through the aperture 1306.Of course, the filter 1320 permits acoustic signals enter the interiorto contact the microphone 1303.

A filter may take a variety of forms. For example, the filter may be ascreen, a gauze member, a PTFE filter, a metal member, or a ceramicmember.

In an embodiment 1500 schematically illustrated in FIGS. 15A and 15B,the housing 1501 is made of laminate structures, including one or moresidewalls 1502 and a top 1503. In the embodiment of FIGS. 15A and 15B, asound pipe 1504 extends from lid 1505, while other embodiments include asound pipe extending from the housing 1501. Further, a number ofinterface pads 1506 reside on the outer surface 1507 of the housing1501. The interface pads 1506 may connect to the substrate 1510,microphone element 1511, and/or ASIC 15121 through conductors on or inthe laminate structures 1502 and 1503.

Some embodiments include a shell outside of the housing and/or the lid.For example, the embodiment 1600 schematically illustrated in FIGS. 16Aand 16B includes a shell 1601 outside of (or surrounding) lid 1602. Anumber of interface pads 1603 reside on the outer surface 1604 of theshell 1601, and may connect to the substrate 1610, microphone element1612, or ASIC 1611 through conductors on or in the laminate structures.The lid 1602 lends structural support to the shell 1601, and may alsoprovide electromagnetic shielding to the microphone system 1600. At thesame time, the shell 1601 provides interface pads on the housing-side ofthe microphone system. Similarly, another embodiment 1700 (FIGS. 17A and17B) includes a shell 1701 outside of (or surrounding) lid 1702.

Another embodiment 1800 is schematically illustrated in FIGS. 18 and 19.In this embodiment, a substrate 1801 has a microphone 1802 and an ASIC1803 on one surface 1801A. A lid 1804 is also coupled to the surface1801A, and covers the microphone 1802 and ASIC 1803, and also spans anaperture 1806 through the substrate 1801. A shell 1805 is coupled to thesurface 1801A, and includes interface pads 1807. The embodiment 1800does not include a housing with a large volume on the side oppositesurface 1801A. However, some embodiments, such as the one schematicallyillustrated in FIG. 18, do include a flanged sound pipe 1808 (i.e.,another type of housing) interfaced with the aperture 1806. It is notethat the inclusion of a shell, such as the shells discussed above, donot require a housing or a flanged sound pipe 1808, even though theexamples discussed above include such features.

As noted above, some embodiments include a filter, such as theembodiment having reference number 2000 and schematically illustrated inFIGS. 20A-C. More specifically, this embodiment includes a filter 2001covering an aperture 2002 in substrate 2003. In this embodiment, thefilter (or “filter material”) 2001 is on the surface 2003A of substrate2003, which is the side of substrate 2003 opposite to the side thathosts/supports an ASIC 2004 and microphone element 2005. In otherembodiments, however, a filter or filter material (or additional filteror filter materials) could be within the aperture 2002, or between thesubstrate 2003 and ASIC 2004.

The filter 2001 may also have acoustic properties that delay the travelof a sound signal. Inclusion of such a filter in a microphone system maybe desirable in a system that has multiple microphone elements, forexample, to adjust the receipt time of a signal by one microphoneelement with respect to the receipt of the signal by another microphoneelement. Alternately, a filter may enhance or accentuate the directionalsensitivity of a directional microphone in which a sound signal reachesa microphone element via two paths between the source of the soundsignal and the microphone element, where at least one of the pathsincludes a filter that delays propagation of the sound signal.

Another embodiment 2050 having one or more filters 2001 is schematicallyillustrated in FIG. 20D. This embodiment is similar to the microphonesystem 400 of FIG. 4, and some reference numbers from that embodimentare re-used in FIG. 20D. This embodiment of a microphone system 2050shows two filters, 2051 and 2052, although the system may alternately beconfigured with only one filter. Filter 2151 occupies a portion of soundpipe 413, or could be coupled to the inner surface of the housing 410covering the pipe aperture, while filter 2152 straddles aperture 402 insubstrate 401, on surface 401B. In addition to introducing an acousticdelay, the one or more filters may serve a more traditional filteringpurpose, such as blocking moisture, dust and other particulate matter orother contaminants, from entering the microphone system 2050, or frompassing through the aperture 402, for example. As in variousembodiments, the sound pipe can alternatively be an aperture.

Some embodiments include multiple microphone packages associated with asingle acoustic port module. For example, an acoustic port module 2101is schematically illustrated in an embodiment 2100 in FIG. 21. Theacoustic port module 2101 in this embodiment includes an enclosed volume2102, and a sound pipe 2103. The acoustic port module 2101 may be metal,plastic, or ceramic, or other material. In some embodiments, theacoustic port module 2101 may include printed circuit board havingconductors and/or interface pads to electrically couple microphonecircuits to a host system.

An external acoustic signal may enter the enclosed volume 2102 via thesound pipe 2103, and pass through to two microphone elements 2104 and2105 via two apertures 2106 and 2107, respectively. In this way, eachmicrophone element 2104 and 2105 has the benefit of sharing a commonsound pipe 2103 owing to the common acoustic port module 2101. Such anarrangement may make the microphone system 2100 more compact thansystems in which each microphone element has its own housing. In someembodiments, exposing the microphone elements 2104 and 2105 to a commonsound pipe (in other words, to a common acoustic port) may facilitateallowing the incoming sound to reach the microphone elements 2104 and2105 at the same time, or with a determinable phase or timedifferential.

The microphone system 2100 also includes coupling elements 2110 and2111. Coupling element 2110 has a tube portion 2112 and a flange portion2113. Tube portion 2112 passes through apertures 2106, while flangeportion 2113 is outside of acoustic port module 2101. The flange portion2113 couples to microphone package 2114 such that the tube portion 2112is acoustically coupled to an aperture 2114A in package 2114. In otherwords, the tube portion 2112 and package aperture 2114A form a holebetween internal volume 2102 and the interior of the microphone package2114. The flange portion 2113 provides a planar surface to meet theouter surface of package 2114. The interface between the flange portion2113 and the package 2114 provides a structural interface, and in someembodiments may create a seal between the acoustic port module 2101 andthe package 2114.

A ball-grid-array mountable embodiment of a microphone system 2200 isschematically illustrated in FIGS. 22A and 22B. A housing 2201 iscoupled to substrate 2202. The housing 2201 includes a sound pipe 2203that passes between solder balls 2204 on a surface of the substrate2202. The diameter of the solder balls 2204 exceeds the height of thehousing 2201, so that the solder balls 2204 may mount to a surfacewithout physical interference from the housing 2201. Such an arrangementallows the microphone system 2200 to have electrical communication witha host system via solder balls 2204, rather than (or in addition to)including interface pads on the housing 2201, for example.

Some embodiments may include more than one ball-grid-array mountabledevice. For example, the microphone system 2300 schematicallyillustrated in FIGS. 23A and 23B includes two such devices, each ofwhich is similar to the embodiment in FIGS. 22A and 22B. Each housing2301 and 2311 includes a sound pipe 2302 and 2312, respectively,although the two sound pipes 2302 and 2312 need not extend in the samedirection. In some embodiments, the sound pipes 2302 and 2312 extend indifferent directions (e.g., at 90 degree angles to one another, forexample) to provide the system 2300 with access to sounds from differentdirections, or to a single sound source from multiple angles.

Some embodiments provide a double-chambered package. Package 2400, asschematically illustrated in FIGS. 24A and 24B, includes a microphonechamber 2401, which houses a microphone 2410, and a backchamber 2402.The backchamber 2402, which may also be thought of as a housing,includes a sound pipe 2420 to allow entry of acoustic energy. Thepackage 2400 may be a molded member, or a combination of one or moremembers 2401A and 2401B. The package 2400 may be of a variety ofmaterials, such as metal, ceramic, or metallized polymer, for example.An outer surface of the backchamber 2402 includes one or more interfacepads 2404 for connecting the package 2400 to a host system.

An aperture 2406 opens the microphone chamber 2401 to the environmentoutside of the package 2400 to allow sound to enter the microphonechamber 2401. An aperture 2403 acoustically couples the microphonechamber 2401 to the backchamber 2402.

Another embodiment schematically illustrated in FIGS. 25A and 25B placesinterface pads 2504 on a surface 2501A of the package 2500 outside ofthe microphone chamber 2501. The backchamber 2502, which may also bethought of as a housing, includes a sound pipe 2520 to allow entry ofacoustic energy.

An embodiment of a multiple microphone system 2600 is schematicallyillustrated in FIGS. 26A and 26B. A microphone 2601 is within amicrophone chamber 2602. The chamber 2602 is acoustically coupled to ahousing 2603 via an aperture 2604 and a coupling element 2605, similarto the coupling elements described above. A second microphone chamber2610 and second housing 2611 are coupled to the first housing 2603 bysolder balls 2606. Each of the housings 2603 and 2611 have a sound pipes2620A and 2620B, respectively, extending outwardly to allow externalsound signals to enter the housing and reach the microphones 2601 and2613. The bottom housing 2611 also includes an array of interface pads2615.

In addition to the embodiments described above, there are a variety ofother ways to connect a sound pipe to a microphone system. For example,FIG. 27 schematically illustrates a microphone package 2700 having abase 2701 and lid 2702 mounted on the base 2701. In this embodiment, thebase 2701 includes an aperture 2701A, and supports an ASIC 2703, and amicrophone element 2704 straddling the aperture 2701A.

The microphone package 2700, in turn, is mounted to a substrate 2710,which may be part of a host system. In particular, the aperture 2701A ofpackage 2700 is mounted over an aperture 2710A in the substrate 2710 sothat the two apertures provide a sound path to the microphone element2704. On the opposite side of the substrate from the microphone package2700 is a coupling tube 2720.

The coupling tube 2720 has a flange portion 2721 and an adapter portion2722. The flange portion 2721 may be secured to substrate 2710 by avariety of means known in the art, such as epoxy or conductive epoxy,for example, and the adapter portion 2722 extends away from thesubstrate 2710 to meet a corresponding sound tube (not shown). The soundtube may couple to the adapter portion 2722 in a variety of ways. Forexample, the sound tube may fit within the opening 2722A of the adapterportion, or the adapter portion 2722 may fit within the sound tube, toname but a few alternatives.

The embodiment schematically illustrated in FIG. 27 also has a washer2730 and a membrane filter 2740. The washer 2730 is coupled directly tothe substrate 2710 within the coupling tube 2720, and helps to seal theinterface of the coupling tube 2720, filter 2740, and the substrate2710. Further, the washer 2730 may be secured to the substrate 2710, andthe filter 2740 may, in turn, be secured to the washer 2730, so that thefilter 2740 and washer 2730 cooperate to secure each other to thesubstrate and/or even to the inside of the coupling tube 2720.

An alternate embodiment shown in FIG. 28 and identified by referencenumber 2800 has a filter 2801 within the aperture 2810A of substrate2810. This embodiment does not include a washer, although a washer couldbe included on the substrate 2810 within the coupling tube 2822.

Other embodiments may forgo the filter and washer entirely, as inembodiment 2900 schematically illustrated in FIG. 29.

Alternate embodiments include a microphone package formed by a lidmounted directly to a substrate within a host system. In other words,the microphone package may forgo a base (e.g., base 2701 in FIG. 27).Such embodiment may still include a filter, such as filter 3140 in FIG.31, for example, or a cooperating filter 3040 and washer 3030 as in FIG.30, for example.

Several embodiments described herein include a sound pipe extending froma housing or a lid. Illustrations of such sound pipes may show the soundpipes as relatively short. However, that is not necessarily the case.For example, FIG. 14 schematically illustrates a sound pipe 1404extending a considerable distance from the microphone system 400. Asanother example, FIG. 32A schematically illustrates a sound pipe 3201Aextending far from a microphone system 3200. In this embodiment, thesound pipe also includes corners or bends 3210.

Other embodiments provide a variety of ways to interface an extendedsound tube to a microphone system. For example an embodiment in FIG. 32Bincludes a sound pipe 3201B extending a short distance from microphonesystem 3200. An extended sound pipe 3202 (which may also be known as a“sound pipe extension”) couples to sound pipe 3201B. In particular, theinside diameter (or inside dimensions) of sound pipe extension 3202 aregreater than the outside diameter (or outside dimensions) of sound pipe3201B such that sound pipe extension 3202 fits over the sound pipe3201B.

In an alternate embodiment schematically illustrated in FIG. 32C, theoutside diameter (or outside dimensions) of sound pipe extension 3203are less than the inside diameter (or inside dimensions) of sound pipe3201C such that sound pipe extension 3203 fits within the sound pipe3201C.

Yet another embodiment is schematically illustrated in FIG. 32D, inwhich a sound pipe adapter 3201D extends into the interior volume ofhousing 3210. Sound pipe extension 3204 then inserts into sound pipeadapter 3201D to guide sound into the housing 3210.

In another embodiment schematically illustrated in FIG. 32E, a soundpipe could interface directly to aperture 3201E.

Various embodiments discussed above therefore provide a system designerwith more choices and greater flexibility in designing the host system,and selecting the shape and size of a microphone module, and locatingand mounting the microphone module within the host system.

The embodiments of the invention described above are intended to bemerely exemplary; numerous variations and modifications will be apparentto those skilled in the art. All such variations and modifications areintended to be within the scope of the present invention as defined inany appended claims.

Although the above discussion discloses various exemplary embodiments ofthe invention, it should be apparent that those skilled in the art canmake various modifications that will achieve some of the advantages ofthe invention without departing from the true scope of the invention.

What is claimed is:
 1. A microphone module comprising: a substratehaving a first side, and a second side opposite the first side, thesubstrate having an aperture extending from the first side to the secondside to allow sound waves to pass through the substrate; a lid mountedto the first side, the first side and lid defining a first interiorvolume, the aperture configured to allow sound to enter the firstinterior volume; a microphone mounted to the first side and within thefirst interior volume; a sound pipe having an open end to receive soundwaves and direct the sound waves toward the aperture; and at least oneexterior interface pad on the second side and electrically coupled tothe microphone.
 2. The microphone module of claim 1, further including ahousing including the sound pipe, the sound pipe having a pipe volume,the pipe volume forming most of a second interior volume, the sound pipebeing mounted substantially flush against the second side of thesubstrate.
 3. The microphone module of claim 2, wherein the housing andat least a portion of the second side of the substrate comprise a pipevolume.
 4. The microphone module of claim 3, wherein the housing beingcoupled to the second side and covering the aperture, the housing andsecond side forming a second interior volume, the housing including anacoustic port configured to allow sound to enter the second interiorvolume, the housing covering no more than a portion of the second sideof the substrate.
 5. The microphone module of claim 1, wherein the soundpipe is straight.
 6. The microphone module of claim 1, further includinga bend configured to allow the sound pipe to run from the microphonemodule to a distal sound source.
 7. The microphone module of claim 1,further including a flange, the sound pipe extending from the flange,the flange resting substantially flush against the second side of thesubstrate.
 8. A microphone module comprising: a substrate having a firstside, and a second side opposite the first side, the substrate having anaperture extending from the first side to the second side to allow soundwaves to pass through the substrate, the substrate having a metalizedportion; a lid mounted to the first side, the first side and liddefining a first interior volume, the lid being formed from a conductivematerial, the lid being electrically connected to the metalized portionof the substrate to protect against electromagnetic interference; amicrophone mounted to the first side and within the first interiorvolume, the microphone being a MEMS microphone; a circuit chip coupledwith the first side of the substrate and being electrically connectedwith the microphone, the circuit chip being mounted within the firstinterior volume; a sound pipe having an open end to receive sound wavesand direct the sound waves toward the aperture; and at least oneexterior interface pad on the second side and outside of the secondinterior volume, the at least one exterior interface pad electricallycoupled to the microphone, the at least one exterior interface pad beingsolderable.
 9. The microphone module of claim 8, further including ahousing including the sound pipe, the sound pipe having a pipe volume,the pipe volume forming most of a second interior volume, the sound pipebeing mounted substantially flush against the second side of thesubstrate.
 10. The microphone module of claim 9, wherein the housing andat least a portion of the second side of the substrate comprise a pipevolume.
 11. The microphone module of claim 10, wherein the housing iscoupled to the second side and covering the aperture and including anacoustic port configured to allow sound to enter the pipe volume, thehousing covering no more than a portion of the second side of thesubstrate.
 12. The microphone module of claim 8, wherein the sound pipeis straight.
 13. The microphone module of claim 8, further including abend configured to allow the sound pipe to run from the microphonemodule to a distal sound source.
 14. The microphone module of claim 8,further including a flange, the sound pipe extending from the flange,the flange resting substantially flush against the second side of thesubstrate.